1. Field of the Invention
The present invention relates to a method for fabricating a semiconductor device, and more particularly, to a method for fabricating a capacitor in a semiconductor device.
2. Background of the Related Art
In general, as high density device packing is advanced, different methods for stable driving of the device are suggested, such as technology employing tungsten-bitlines or cobalt suicide in case of embedded DRAM. However, the tungsten-bitline limits heat treatment conditions after formation of the tungsten-bitline, and to prevent device deterioration, the heat treatment after the bitline formation is limited to be carried out at 800xc2x0 C. within 10 min.
A related art method for fabricating a capacitor in a semiconductor device will now be described with reference to the attached drawings. FIGS. 1Axcx9c1D illustrate cross-sections showing the steps of the related art method for fabricating a capacitor in a semiconductor device.
Referring to FIG. 1A, a plurality of wordlines 13 are formed on a semiconductor substrate 11 with an insulating film 12 inbetween. A first impurity diffusion region 14 and a second impurity diffusion region 14a are formed in the substrate on both sides of each of the wordlines 13. Then, a first insulating layer 15 is formed on the semiconductor substrate 11 inclusive of the wordlines 13 and subjected to photo etching to selectively remove the first insulating layer 15 and form a bitline contact hole 16 that exposes the first impurity region 14. As shown in FIG. 1B, a bitline 17 is formed, which is electrically connected to the first impurity diffusion region 14 through the bitline contact hole 16. The bitline 17 is a stack of layers of titanium (Ti)-titanium nitride (TiN)-tungsten (W) in sequence. A second insulating layer 18 is formed on the first insulating layer 15 inclusive of the bitline 17. The second insulating layer 18 and the first insulating layer 15 are selectively removed by photo etching to form a storage node. contact hole 19 that exposes the second impurity diffusion region 14a. 
As shown in FIG. 1C, a conductive material 20 is deposited on the second insulating layer 18 inclusive of the storage node contact hole 19. A planarizing is conducted to stuff the conductive material 20 in the storage node contact hole 19 in electrical connection to the second impurity diffusion region 14a. Then, a material for a capacitor lower electrode is deposited on the second insulating layer 18 inclusive of the conductive material 20 and patterned to form a capacitor lower electrode 21 electrically connected to the conductive material 20. Then, a Rapid Thermal Nitridation (RTN) is conducted at approximately 800xc2x0 C., to form a nitride film 22 on a surface of the capacitor lower electrode 21 to a thickness of 7xcx9c15 xc3x85. Then, a Ta2O5 film 23 is deposited on the nitride film 22 as a capacitor dielectric film, and subjected to dry-O2 heat treatment in a furnace at an elevated temperature higher than 800xc2x0 C., to form an SiON film 22a at an interface between the Ta2O5 film 23 and the capacitor lower electrode 21 as a result of oxidation of the nitride film 22. The SiON film 22a is shown in FIG. 1D. In this instance, a Rapid Thermal Oxidation (RTO) may be employed in place of the dry-O2 heat treatment at an elevated temperature higher than 800xc2x0 C. The high temperature heat treatment is carried out to improve leakage current characteristics. Then, an upper electrode 24 is formed on the Ta2O5 film 23 to complete fabrication of the related art capacitor.
As described above, the related art method for fabricating a capacitor in a semiconductor device has various disadvantages. First, as the high density device packing advances, a load on a bitline is increased. When a tungsten-bitline is employed for solving this problem, a heat treatment temperature required for formation of the capacitor is limited. When the Ta2O5 film 23 is heat treated at a temperature equal to or higher than 800xc2x0 C. for more than 10 minutes, the tungsten of the bitline is deformed, which causes an increased resistance. Further, an inter-diffusion between the substrate and the bitline increases a bitline resistance. Second, when a capacitor in an embedded DRAM is formed, a dry-O2 process that requires a temperature higher than 800xc2x0 C. can not be applied in formation of a Ta2O5 film. Third, RTO may be employed in place of dry-O2 heat treatment. However, RTO requires much more time because diffusion of the oxygen ion is slow.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
An object of the present invention is to provide a method for fabricating a capacitor in a semiconductor device that substantially obviates one or more of the problems caused by limitations and disadvantages of the related art and to provide at least the advantages described hereinafter.
Another object of the present invention is to provide a method for fabricating a capacitor in a semiconductor device that decreases or prevents a device deterioration caused by heat treatment.
Another object of the present invention is to provide a method for fabricating a capacitor in a semiconductor device that improves a leakage current characteristic.
Another object of the present invention is to provide a method for manufacturing a capacitor in a semiconductor device that increases device reliability.
To achieve at least these objects and other advantages in a whole or in parts, and in accordance with the purpose of the present invention, as embodied and broadly described, a method for fabricating a capacitor in a semiconductor device includes forming a nitride film on a capacitor lower electrode, depositing a Ta2O5 film on the nitride film as a capacitor dielectric film, and heat treating by a rapid thermal process using N2O gas to form an SiON film at an interface between the capacitor lower electrode and the Ta2O5 film, and forming a capacitor upper electrode on the Ta2O5 film.
To achieve at least these objects and other advantages in a whole or in parts, and in accordance with the purpose of the present invention, as embodied and broadly described, a method for fabricating a capacitor in a semiconductor device, the capacitor using Ta2O5 as a dielectric film, the method includes the steps of (a) forming a wordline on a substrate, (b) forming first and second impurity diffusion regions in the substrate on opposite sides of the wordline, respectively, (c) forming a bitline electrically coupled to the first impurity diffusion region, (d) forming a capacitor lower electrode electrically coupled to the second impurity diffusion region, (e) forming a nitride film on a surface of the capacitor lower electrode, (f) depositing a Ta2O5 film on the nitride film and performing a heat treatment by a rapid thermal process using N2O gas to form an SiON film at an interface between the capacitor lower electrode and the Ta2O5 film, and (g) forming a capacitor upper electrode on the Ta2O5 film.
To achieve at least these objects and other advantages in a whole or in parts, and in accordance with the purpose of the present invention, as embodied and broadly described, a method for fabricating a capacitor in a semiconductor device includes forming a nitride film on a capacitor lower electrode, depositing a Ta2O5 film on the nitride film, performing a rapid thermal process heat treatment process conducted in the range of approximately 650xcx9c750xc2x0 C. that forms an SiON film at an interface between the capacitor lower electrode and the Ta2O5 film, and forming a capacitor upper electrode on the Ta2O5 film.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.